Unfortunate mishap after first hard rainfall.
No further information available
Personal Comment by Quizmaster Judy Pfaff
How Collier Solved the Puzzle
If you have a picture you'd like us to feature a picture in a future quiz, please
email it to us at If we use it, you will receive a free analysis of
your picture. You will also receive a free
Forensic Genealogy CD or a 10%
discount towards the purchase of the
Forensic Genealogy book.
If you enjoy our quizzes, don't forget to order our books!
Quiz #360 Results
Bookmark and Share


1. The Moses Bridge
2.  Municipality of Bergen op Zoom, The Netherlands
3.  Using two adjustable dams on either side of the moat,
with a small pump under the bridge to drain rainwater.

Unfortunately, the dams and the pump do not work well, and the bridge
flooded during the first heavy rainstorm.  See pictures below.
Answers to Quiz #360
July 15, 2012
1. What is the name of this bridge?
2.  Where is it located?
3.  How does it keep the inside from flooding when the water rises?
Comments from Our Readers
[How does it keep the inside from flooding when the water rises?]

From some of the photos I found, often it doesn't!! However to minimise, the walkway
has drains under it, the height of the water in the moat is restricted (all the sites keep
saying "remember this is the Netherlands!" and from the architectural plans I found,
there is a sump pump. So the water drains through the slatted walkway to a sump and
is then pumped out to the moat. This would work for light rain and for windblown
water, but not for any real flooding issues. See these photos of "When sunken bridges
go bad..."

Ben Hollister

My first reaction to the photograph was the obvious.  Moses did that!  (Only he didn't
need a construction company.)  So, when I found the name of the bridge, it was no
surprise.  This is the Moses Bridge which crosses the moat to an old fort.

Carol Farrant

This was fun!  Trust the dutch to come up with a unique design to hold back the
water.  I started by googling "unique bridges". This was too broad so I tried "unique
walking bridges + underwater" and I found the following images at

I checked the architects website and found that they were finalists for the 2011 Dutch
Design Awards.  The site is in Dutch so ???

Thanks for another fun challenge.

Debby Was

What an interesting bridge! I'd love to cross it someday. Thanks for a good quiz about
an interesting item Colleen.

Charlie Wayne

It has a drainage system at the bottom in the middle and there is a schematic of the
design online, but with my aged eyes I cannot see it well enough to figure out how it

Dennis Brann

N.B.  I can't read the fine print either, especially since it's in Dutch.

An interesting bridge design. Invisible to every one except those next to it. Nothing I
found mentioned a draw bridge for the original Fort. This design satisfied the

Your email of 7/21 put me on another search. A discussion by the designer of the
bridge said there were two flood control dams at opposite ends of the moat to control
the water level. A pump was to drain the bridge when it rained.

I found a newspaper article that said the first rain clogged the pump(probably leaves)
and the bridge filled. I can't find that site. This changes my answer to Q3.

Q3 Two flood control dams and gates at opposite ends of the moat control the water
level. A drainage pump is supposed to keep the inside dry. It clogged and failed the first

Arthur Hartwell

N. B.  Thanks.  This restores my faith in Dutch dam-building if it was only a matter
of leaves clogging the pump. That's easily fixable.  Now it's the bridge itself that
requires major repair, accoya wood or not. - Q. Gen.


Do you think that overflow system is like the ones we have in bathroom sinks? The
overflow holes would have to be on the outside of the bridge.  Where would the excess
water go?   It wasn't clear to me as to how that works.  I would think closing off the
moat inflow would be possible too.  Wouldn't it be fun if the bridge could be floating
and just rise with the water level?  This would be sort of  like shipping locks where
water is let in one end and the ship rises and is let out the other end.

I did guess the first two questions you would ask.  The third was not what I expected.  
Why was the bridge build in the first place?  or What kind of wood can withstand being
in the water?

Some people don't like crossing bridges (Gephyrophobia) and some don't like being in
tunnels.  Is there a fear of crossing this kind of bridge-tunnel?

I like your quizzes and answers.  Puzzle on.

Judy Pfaff

A dear friend of mine is an architect/engineer. He is beyond fascinated with this bridge
and shared photos of it with me about a year ago. I really hope to get back to The
Netherlands again just to go see this modern wonder.

Sally Garrison
Congratulations to Our Winners!

Donna Jolley                Linda Wilbur
Gus Marsh                Judy Bradley
Ben Hollister                Joshua Kreitzer
Carol Farrant                Janice Sellers
Debby Was                Charlie Wayne
Robert Austin                Jim Kiser
Janice Kent-Mackenzie                Audrey Nicholson
Anne-Marie Laberge                Claudio Trapote
Marcelle Comeau                Dennis Brann                Peter Norton
Daniel Jolley                Nelsen Spickard
Shirley Hamblin                Christine Walker
Tish Olshefski                Arthur Hartwell
Collier Smith                Debbie Johnson
Maureen O'Connor                Louise Gunkel
Angel Esparza                Rebecca Bare
Judy Pfaff                Margaret Paxton
Sally Garrison                Bill Utterback
Mike Dalton                Tim Fitzpatrick
John Roberts                Diane Burkett
How the Moses Bridge Works
Ad Kil, who with Ro Koster makes up
Ro&Ad Architects, was kind enough to
send some information on how the the
Moses Bridge (the bridge that cuts
through a moat in the Netherlands) works
and was built.

According to the designers, virtually no
water spills over the edge because the
height of the water is controlled by two
small adjustable ‘dams’ at both sides of
the moat. The dams are set at a height to
Ad Kil and Ko Roster
Architects of the Moses Bridge
ensure that when the water level rises, the water spills over and into the dams and not
into the bridge. In case of a heavy rainstorm, a small pump under the bottom of the
bridge evacuates the water.

The Moses Bridge was built in about 2 months in the middle of the moat waters by first
dredging around the bridge site and then driving sheet piles into the ground, as shown in
the photos below.
The Moses Bridge
2011 Building of the Year
Architects:  RO&AD Architecten
Location:   Halsteren, The Netherlands
Client:       Municipality of Bergen op
Material used:  Accoya wood
Project Area:    50 sqm
Photographs:    Courtesy RO&AD
I could not find much discussion of the means for keeping the water
out of the bridge. However, it appears from the many photos that it is
not articulated to move up and down. In fact, since there is a huge
upward force on the bridge equal to the weight of the displaced
volume of water, the bridge must be strongly anchored to the bottom
of the moat, probably by hundreds of tons of concrete in the
foundations. Therefore I conclude that the water level must be
controlled instead, probably by means of a spillway not too far away
set about 3 inches below the top of the bridge. Or, since this is
Holland, perhaps they have a really big pump standing by. Any casual
water that might come in from rain, small waves, leaks and the like,
could be removed by a small pump or two in sumps below the
walking surface.

I googled (not image-google) "bridge below water line level" and 4 of
the first 5 hits were of this Dutch bridge. On google-images using the
same terms, I got even more hits on the first page. The Wiki article
on the fort gives Lat/Long. I found that the satellite image does not
seem to show water in the moat, nor the bridge.

Collier Smith
My Dad took us on trips to the Upper Peninsula of Michigan to the
road that was lower than the river.  It was called the Manisque siphon

The so-called siphon bridge here was once featured in Ripley's
"Believe It or Not" newspaper series. Here the highway was actually
below the river level. Its water actually supported the bridge.
(Highway reconstruction has now removed this novel feature.) The
1941 Michigan Guide, by the WPA Writers' Project, explained the
purpose of this unusual structure:

"In 1916, when the Manistique Pulp and Paper Company was
organized, engineers realized that a dam at the mouth of the river [that
was] large enough to supply the needs of the mill would flood a large
section of the city. If the shallow river banks were diked to hold the
water, bridging the river would be expensive. The problem was
solved by constructing a huge concrete tank lengthwise in the river
bed; the sides of the tank provide artificial banks, higher than the
natural ones.

Concrete bulkheads, formed by the side spans of the bridge, allow the
mill to maintain the water level several feet above the roadbed."

Judy Pfaff


N.B.  This isn't well written and hard to understand.  It's very
confusing about the relationship between the dam, the dikes,
and the bridge.  

But I think I understand.

I gather that the Manistique Pulp and Paper Company built
their dam to supply their mill with water. But instead of building
dikes along the banks of the river to protect the town, along
with a bridge to cross the river, they just built one structure -
the bridge. But they built the sides of the bridge way high, to
hold the water back from flooding the town. The extra water
collecting in the dam's reservoir on the upstream side of the
bridge was prevented from reaching the town on the
downstream side near the mouth of the river by the high
concrete walls of the bridge.

Kind of like driving on the road over the top of the Hoover dam,
but different.

Well that's about as close as I can get at the moment.

- Q. Gen.
Ode to a Sunken Bridge
by John Roberts

A walkway, the Netherlands has
so that visiting tourists can pass
to the Fort de Roovere,
and back, with no fear.
Is it cool?  Why, you bet your bottom dollar!

John Roberts
We are dynamic and unconventional.
Breaking fresh ground, broadening
horizons, making connections. We are full
of ideas, conceptual, skilful, free from
styles and full of style. Sustainability,
clarity, enthusiasm, freshness. These are
some of the words that come to mind
when describing our collaboration and
practice. We have been working together
structurally since 2002, combining over 30
years of experience under the name
RO&AD architecten.

One of our strongest points is coming up
with ideas. We are true idea makers.
Concepts always come before design.
RO&AD Architects
Plans are stronger when design is firmly based on a good concept. Concepts can steer
design in all stages, from development to execution. This results in plans that speak the
same language on all levels, making them clear and transparent as well as well
thought-out and layered. We seek out the essences and issues of an assignment and let
them fertilize each other.

We have been working at making our building projects and products more sustainable
for a number of years now. After having watched the documentary Cradle to Cradle ,
we became convinced that the cradle-to-cradle philosophy combined with our input can
make a better, economically makeable and happier world. We therefore try to
incorporate this insight into our designs as much as possible.
The West Brabant Water Line is a defense-
line consisting of a series of fortresses and
cities with inundation areas in the south-
west of the Netherlands. It dates from the
17th century but fell into disrepair in the
19th century. When the water line was
finally restored, an access bridge across
the the moat of one of the fortresses, Fort
de Roovere, was needed. This fort now
has a new, recreational function and lies
on several routes for cycling and hiking.

It is, of course, highly improper to build
bridges across the moats of defense
works, especially on the side of the
fortress the enemy was expected to
appear on. That’s why we designed an
invisible bridge. Its construction is entirely
made of wood, waterproofed with EPDM
foil. The bridge lies like a trench in the
fortress and the moat, shaped to blend in
with the outlines of the landscape.

The bridge can’t be seen from a distance
because the ground and the water come all
the way up to its edge. When you get closer, the fortress opens up to you through a
narrow trench. You can then walk up to its gates like Moses on the water.
Location of bridge
51 deg 31' 38" N, 4 deg 18' 05"E
near Bergen op Zoom, Netherlands.
Bergen op Zoom in 1649. Note marshes
(left, top right), canalized diversion of
the Scheldt and extensive fortifications.